Written by [IGN: Stromae]
For the first SS, your priority will be getting a tank SSR (Shiva, Asura, Wukong, Amaterasu) with 1 or 2 SR
If you end up getting a good dealer ssr and good sr, you might as well take it.
For the second SS, your priority will be dealer or tank (get dealer if you got tank on first SS, vice versa).
List of good units you might go for:
Tanker: Shiva > Wukong > Amaterasu - Arioch - Asura > Ceryneia > Thor
Dealer: Tyr - Baphomet > Susanoo > Odin - Ea - Mithra - Brynhild > Lucifer - Hastur > Yamatano Orochi - Indra
Support: Enki - Zeus > Aurora
Tanker: Seth > Metatron - Ares > Geb - Guan Yu - Athena > Azazel
Dealer: Chimera > Nine-tailed fox - Yuki - Morrigan - Tsukuyomi > Skuld - Izanagi - Verdandi
Support: Loki > Isis - Urd > Ra - Mephisto
Tiamat & Michael
To start with good units, you might want to have Shiva + Tyr from first 2 SS and Seth/Loki/Chimera SR.
Build Tiamat and Michael as they are easier to get and will help alot in PVE and PVP.
Optional to build Werewolf Warrior. It's capable of removing ALL enemy target barrier and deal damage after that.
Note: All of SSR and SR units are great, the tier list was just based on how they do in early game. Thor can be better than Amaterasu depending on your squad composition and the situation of the battle.
Learn to build a great team with their relics effects and skills effects, so you wont need to rely on others for judging which unit you should get that match your team.